Interesting, Todash. I do recall reading years ago that Pepsi stimulated some of the same taste buds that citrus juices stimulate, whereas Coke stimulated the same taste buds as cocoa products.
I first saw these in Chicago last year shopping. The only problem is that people spend a little too long making selections and backs up the whole drink dispensing process.
My local BK has one of them things. Not sure how many different flavors it offers, but I'd say it's at least a dozen.